The only problem with that, and I agree that it would be great for Angel to have some Slayers on his side, regardless of who they were, is that Los Angeles is in Hell and no longer accessible to our world (at least that's my impression of the situation). For all we know, the rest of the world may not be aware of what happened. For whatever reason, I don't see there being any sort of communication between LA and the rest of the world, or any access between the two, so I wouldn't look for Faith anytime in the near future.
Having said that, it's not inconceivable that either Giles or Buffy might have had a team of Slayers hanging around LA keeping an eye on the goings on at Wolfram and Hart the same way Angel THOUGHT that he was having Buffy watched in Rome. If so, and the girls survived, they might make some effort to hook up with Spike and Connor, since they seem to be the ones doing most of the rescue work around the city. I seriously doubt that they would have a whole lot of trust in Angel, especially if they were aware that the "stand" that he took against the Senior Partners was directly responsible for the entire situation there in LA/Hell.